Hydrocarbon treating process



Feb. 16, 1960 G. T. GWIN ETAL HYDROCARBON TREATING PROCESS Filed May 19, 1958 NAPHTHA FRACTION FRACTIONATIOQI ZONE CATALYTIC CRACK'NG ZONE FRACTIONATION PREHEATER HYDROGEN PREHEATER STRIPPER lNVEA/TORS. GILMORE-T. ewm.

aovo N. HILL,

STRIPPER uoumsn DEASPHALTING PROPANE zone ASPHALT RICHARDS. MANNE,

D R E H P E H T S E E w P R E P G KR o I E NG Y B ciujmyjm. so BY, ATTORNEY.

h ng-y nradson carbon content wi hin th ,Ps e t d r'eb, tat 1960 25 a .tlxanocmournnamemocasst Gilmore r. Gwin, Boyd- N. Hill, Richard s. M'aune; Nick range ofiabout ifimllto p.s.i. g.-,-a,v temperature vvithin P. Peet, George R. L.' Shepherd, and Armand Mt Souhy, all of Bnytown,v Text; assignms, bymesne. 'assignments; E580. Research-and En ineering; C mp ny; Elizabeth,N- macnrp t o z fi'De a aei Application May 19, 195s;seriat-No lssofir 6 Claints. c1; ,zos- -sog This invention relates to. a. method. for thetreattnent oi heavyl' petroleum crude oilfractions More particu- Karly,v this invention is directed to a method for treating heavy; petroleum crude, oil fractions; in order toro gain an enhanc d y ld of gh qu ty talytic, racking e d tock. 7

In the refin ng Qf' d P tr leum, itg sgiene i 'si si able to minimiz he y el f sid lf i si n-f v r t ighte ga o in an si llqheating oil fractions. Thus, it is, common practice to catalytically'crach' virgin gas .-oil' distillate fractions in the presence of a suitable.crack ing catalyst such as a silica-alurnina catalyst inorcle'rlo hvdrocarbon fractions which. are; best suited characteriied' by .a relatively high naphthenesjcontentrelatively low aromatics "content, a: relatiyely lowpo f rads on carbon content, and a relatively low metals conorganomet'allic compounds of nicke1, "ir o'n, and,

tent (i;.e=., vanadium)". a

g It has heretofore been proposed toenhanceithe arnount of catalytic cracking feed stock obtainablle frorn the crude petroleum by treating a virgirfresiduurn fraction withfa' liquefied normally gaseoushydrocarbon in the presence oia Wash oil in order toobtain a high-boiling: deasphal'ted oil. Sucha process-isdisclosed; for example; in copending P'eetapplication Sen No. 493-371; filed March 1'0;

Thus thehfionradson carbon, content ofthe deasphalted oil; isgloweiie'clrtor'a value of about ,4. weight percent or less. it would not be. expected that such a reduction I 1955 and entitled Solvent-Deasphalting of- Residual 011s 1 with Wash Oil to Remove- Metal Contaminants-' ('now US; Patent No. 2,853,426). While-animproved recovery of catalytic cracking feed jstock components is obtain able by a method of this nature; therresults still; leave much to be desired in thatpotential-"catalyticcracking feed stock components are still 'discardedg "Heretofqre;

tivegwith respectto Conradson: carbon reduction; 7 Thus, it has been discoveredl inc-accordance with the present: invention .that a". limitation on the deasphalting step is-rimposedib'y. the-'Conradsonvcarboncontent, metals a V '50 1 this has been the case inthat a wash oil is elfective for 3 removing metal; contaminantsbut comparatively inefiecf' content, andaromatics content of the deasphalted oil in a that unsatisfactory results are obtained in. catalytically cracking deasphalted oils having a. Conradson carbon contcntzin: excess oflabout 4- we'ight "percent and a nickelcontent-tin excess of about 1" part. per'millio'n (p.p.m .)r.

It hastnow. been; discovered that'-'the above and similar problems may: be; overcome through the .provision 'of .a

process wherein a petroleum hydrocarbon; crude oil residuumrlfraction'tisfig dmearbona under conditions to -provide ;a ,deasphaItfedLoiI about; 4.5; to; 6 5 weight percent; and wh erein Y (b1 The, thus-prepared deasp alted' oil is sub ctedto.

"rangeqof i F a mild hx m na qnt n; hejn essn ex fzaseb ltr iiql hdat catalystunder conditions including a pressure within the lyticj erackina ait- 1' s Still furthen'there is, a s

2 210 e sl xvsa eyle abottoms lineZG'containinga'pump'22L I The thus-obtained bottoms, fraction is: charged to; a

t e al fisw eba r r ili liqu fied normally gaseous.

the range oi aboutfili to 275 FL, a space. velocitywithin the range Qfifabout lflto 3. v.'/v. /hr.,; and a hydrogen charge rate di a-bout 40.0 to, 2000 cubicfeet of hydrogen per barrel of feed. The conditions should bevsuch that not morethan ahqut'ipercent ofi'the feed: stock-isconvetted to-lower bgilirig hydi ocarbon products. v V v When thi iis done, 1 numerous advantages are obtained,

puljdibe obtainable under the mild hydrogenation conditions that e lined in. that the feed. stockis a high 1201LIIEIQKIYQXIQEEQQQW mate 7 H sentiment the e. is v.01: t limtd um s y hanced red ction, n e. mount o metalc n m a This is of particulanjin portance in thatvmetal contaminants h as" nicke iro and vanadium ad er ly affect yt c. qraqkinggreactians ev I n ucli ont minants are present in'qnly trace amountsjnithe feedt stockto 21; C313:

Tuining now foiF onst c on such. asan atm s il -j Ps m eu h 'tt actiqnatia zo e. y, Way

' a of! a eil eeu fiif nsurance in; n i pn m n a .n .v dis lla qf lastiq s eh 'an o er; he d nap thafmc on Me i il atefuel 0.1 1 te t fqnv 1 p vl tie a l e and aivirgi'n' gasf'oil fraction 1,8bo iling within the range of about GSQfto about; 950 :F'. A rcs idnun fractiqn 2O comprised principally of coinponents boiling. above. about 9i0 B 1 is discharged firqrn thezone 1:01 by way of e e i "19m i'w s' f a o r etiensu hthat the tes imafiea e m be: t ea ed th a: li uefi d nerma w; sa eousi s i qarben su h liquefied propane iqus gedib e e. ra'm tureth r o nhalj g tow r t qmgityantne t v wav of, acharge line 25 andltthe, reslduunilftaction chargedltot the tower ad! halt fraction which; isdischarged. from Wofa bottoms line-26 'andla solu ion,offldea phal esl hydrocarbon.

v i i {catalytic cracking cycle stoc having at-specificggravity Y Y (a ),Deasphalteclwith;aQliquefid;normally gaseousihyr t 'n- 7 fns the nrocessiof v I; there is shown sanctioning I l hyd c rbon 4' dr win n. t'o'r'ie l to pro d As has been indicated, the deasphalting step is conducted in accordance with the present invention in order to provide for a deasphalted oil'having a Conradson carbon content within the range of about 4.5 to 6.5. This may be accomplished by utilizing a comparatively lower deasphalting temperature, a comparatively larger amount of liquefied normally gaseous hydrocarbon, or a liquefied normally gaseous hydrocarbon containing a comparatively large amount of butane. g

By way of example, in deasphalting a West Texas crude residuum to obtain a deasphalted .oil having a Conradson carbon content of about 3.5 weight percent, the solventto-oil ratio may be about 4:1, the solvent may consist of a mixture of about 70 volume percent of propane with 30 volume percent of butane and the deasphalting temperature may include a temperature of 180 F. at the top of the tower and a temperature of 160 F. at the bottom of the tower. In obtaining a deasphalted oil having a Conradson carbon content ofrabout 5.5, there may be employed the same solvent-to-oil ratio but the solvent in this situation may consist of a. mixture of about 62 volume percent of propane with. about 38 volume percent of butane. The deasph'alting temperature may include a temperature of 150 F. at the top of the tower and a temperature of. 130 F. at the bottom of the tower.

The solution of, deasphalted oil in liquefied normally gaseous hydrocarbon is withdrawn from the top of the deasphalting tower 24 by way of a discharge line 30 and passed to a suitable stripping zone 32 wherein the liquefied normally gaseous hydrocarbon is flashed from the deasphalted oil, the volatilized hvdrocarbon'being discharged from the stripping zone 32 by way of a line 34. I 1 i The deasphalted oil is discharged from th e stripping zone 32 by way of a bottoms line 36 containing a pump 38 leading to a preheater 40 wherein the deasphalted oil is preheated to a temperature within the range of about 625 to 725 F., resulting in an average reactor temperature of about 675 to about 775 F. The preheated cracked in vapor phase in the presence of finely divided silica-alumina cracking catalyst.

The effluent from the catalytic cracking zone 62 may be charged by way of a line 64 to a fractionation zone 66 wherein the catalytic cracking product may be separated into a plurality of fractions including a gaseous hydrocarbon overhead fraction 68 a high octane naphtha fraction 70, a heating oil distillate fraction 72, a gas oil boilingrange distillate fraction 74, and a bottoms residuum fraction 76. I

It'is a feature of the present invention that the yield of high octane boiling range naphtha is enhanced by the feed pretreating' process of the present invention and that, moreoventhe octane number of thethus-obtained naphtha fraction is increased, as compared with the octane number otherwise obtained.

It will be understood that the deasphalted oil obtained from the stripping zone 32 may be admixed with avirgin gas oil boiling range hydrocarbon fraction, such as the fraction 18. In this situation, the virgin gas oil. fraction is pumped by means of a pump 78 to a branch line 80 controlled by a valve 82 leading to the charge line 36 for the preheater 40. When this is done, the quality of the virgin gas oil is materially enhanced through the substantial removal of sulfur therefrom. Alternately, of course, the valve 82 may be closed and a valve 84 in the line 18 may be opened whereby the virgin gas oil will be directly charged to the preheater 58 for the cracking zone 62.

It will be further understood that, if desired, the gas oil distillate'fraction 74 obtained by fractionation of the products from-catalytic cracking maybe pumped by a pump 86 'to a recycle line 88 controlledby a valve 90 leading to the charge line 54 for the preheater 58 of by a valve 94 leading from the recycle line 88.

feed stock has admixed therewith an amount of a hydrogen-containing gas. sufiicient to provide for about 400 to 2000 cubic feet of hydrogen per barrel of feed stock, the hydrogen being introduced by way of a hydrogen charge line 42. a

The resultant mixture is charged to a hydrotreating zone 44 containing a bed of cobalt molybdate catalyst, the catalyst preferably being utilized in pilled form. A

suitable catalyst may comprise from about 10 to 20 weight 7 percent of the oxides of cobalt and molybdenum sup ported on high surface area gamma alumina;

As indicated, the hydrotreating conditions employed within the zone 44 include a pressure within the range of about 650 to 950 p.s.i.g.. anaverage reactor temperature within thefrange of 675' to 7.75"'F., and aspace velocity within the range of about 1 to 3 v./v./hr.

The product from the hydrotreating zone is discharged therefrom by way of a line 46 containing a pump 48 leading to a stripping zone'50 wherein gaseous 'compercent, such product constituting a good quality feed.

stock for catalytic cracking.

.Thus, the hydrotreated product may be charged by 7 way of the line 54 to a preheater 58 and from thence by way of a line 60 to a catalytic cracking zone 62 of any suitableconstruction. Thus, for example. the crack ing zone may comprise a fluidized catalytic cracking unit wherein at least a portion ofthe feed stock is catalytically As a specific example of the present invention, a West Texas petroleum hydrocarbon crude oil may be charged to the fractionation zone 10 by way of the charge line '12 and there fractionated to provide a gas oilfraction 18 boiling within the range of 650 .to 950 F. and com stituting about 33 volume percent of the crude oil. A residuum fraction constituting about 12 volume percent of the crude oil may be discharged from the zone 10 by way of the line 20 and thereafter deasphalted in the zone 24 to provide a deasphalted oil having a Conradson carbon content of about 5.2 weight percent. In this situation,'about 60 percent of the residuum fraction 20 is recovered as deasphalted oil, as contrasted with about a 45 percent recovery when deasphalted sovas to obtain a deasphalted oil having a Conradson carbon content of about 3.5 weight percent; i

The high Conradson carbon content deasphalted ,oil may thereafterbe separated from the liquefied normally gaseous hydrocarbon solvent in thestripper 32 and passed to the hydrotreating zone 44' wherein the deasphaltedoil may be subjected to hydrotreating conditions as set forth above. tent of the deasphalted oil is reduced by. about-30 to 50 percent to provide for a hydrotreated product having a Conradson carbon content of about 3 to 4 weight percent. Thus, an additional 15 volume percent of the'residuum fraction may be utilized as catalytic feedstock through the provision of the process of the present invention due to the satisfactory reduction of Conradson carbonthat is obtained. V l

Further advantages are obtained. For= example,- the nickel content of the high Conradson carbon content deasphalted oil is reduced by about .60 to 70 percent As aconsequence, the Conradson carboncon- '7 b'o'n content of about "to 6T5.

cent Conradson carbon cbritent 'willcontain about .10 to 40 percent more nickel thamthe product obtained by hydrotreating a deasphaltedoil haying-a Conradson car- In addition, there is about a lo to Improvements of this. nature ar na obtainable with other residuum treating processes. For ex m le, hydrotreating of the entire'residuum fraction Without an intermediate deasphalting stefiwill provide a catalyticifi acking feed stock having aihighermetals contenf'and a'higher aromatics ring content. Still Ifuftlie'r, a qut percent less catalytic cracking feed stock -is obtained by direct hydrotreating of the entire residuum fraction as contrasted with the deasphalting-hydrotreating pio'c'ess' of the present invention. In similar fa'shio'ii, afedii'c'e'd yield and inferior quality of catalytic cracking feed stock, as

compared with the process of the qiresent iinvention, is experienced when the entire Presiduum is subjected to A West-Texas petroleum hydrocarbon' crude oil was fractionated to obtain a residu'urn fractionboiling abdve about 950 F. and constituting about ':1-2.7 vo1ume"-percent of the crude oil. 1

A first portion of the-residuum fra'ctibn' was'd'eas phalted in a deasphalting tower with a=liquefied "mixture vide a deasphalted oil having {a' Conrad son carbon pen- -'tent of about6.5 weight'percent 1 e fearter ;erer;e to

as DD feed stock).

.. 'f fitx 'tion' in aromatics ring content; fo'r't'h'e hydrotiea'td prod- .uct as compared with the high Conradson carbon content deasphalted oil and a sulfur reduction within the range of about '40 to 60 percent.

Tenoerature, i .700. Liquid Yield, Vol. Percent. 97.3 Product Gas, s.e.t'./b 496 Desulfurlzation, Wt. Perce'nt- 41 Feed 1 Inspections on Total Product: 1 Gravit API .17.. 20.1.; 1 8.0

Sulfur, Wt.--Percent: i 0143 0.61 Conradson Garbon; Wt.

Percent 05 8 4:1 i' W "0'52" 1 66 r :m

V, p 0.64 1. Fe, p=p:m 0:35; 0.55 Aromatic W cent: 13:4 13. 9

Front Table I it will be observed that with the first .(DC) feed stock a product was'obta'ined having a 66h i'adson carbon content of about i we g'h't- 'ierce'iit. Still further; *the yield-of liquid pro'ductswas in excess-bf 97 percent. It wasnifwEir'thy ,thatthelnickel content of the product was-lessthan about 1 ppm. whereas the n e s lfi i 5f fi fi st ck. wa b .35%. 12-12- 1 A similar result was obtainedwith the second (DD) feed .stock. 1

stock, the conversion conditions employed inthe treating operation, and the results obtained are set forth as the catalyst for assume Run N 'Prd'ce'ss' Conditions:

Temperature, F 750 Liquid Yield, Vol. Percent" 03. 101. 6 Product Gas, s.c.f./b 9 435 410 474' 413 Desulfurization, Wt; Percent 62 -01 46 a 53 Feed Inspections on Total Broduct:

ravi ty "KPL; 16.0 18.7 18.0 17.1 v17.8 18.1 P Sulf ur LPe'rcenL. 1.37 0.52 0.72 0.95 0.74 0.64 e Gonra'dson Carbon, Wt. Percent. 5. 2 3.2 3.2 4.2 3. 5 2. 5

-Mo1ecular Wei h't' "Nif 0.82 0.32 0.48 0.52 0.44 0.44 A V 0.34 0.04 0.12 0. 30 0. 30 0. 30 A a m p 2.10 0.40 0.45 0.40 0.55 2.70 Aromatic Ring Wt; Percent 18.5 16.0 17.6 16.6 15.9 15.1

Each of the thus-prepared ifeed" stocks was thereafter The inspections ofthe two feed stocks, the hydro- 7o m Table Kit is seen thatin each ins tance products g areduced metals content and a reduced Conrad- DB-3 wherein the treating conditions included a space velocity ofabout 4 v./v./hr. that an undesirably low removal of sulfur was obtained. 7

3a 't'heresu lts obtained in TableII. The catalyst-for Example II was the same sojn;c arbon content were obtained. Note, however, from QQWEB- Table III HYDROTREATMENT OF BLEND F HEAVY GAS OIL AND VIRGIN GAS OIL,

Blend Composition, Vol. percent:

Deasphalted Oil (16 API) (Table II) 35 Virgin Gas Oil (24 API) 65 Conditions: I

Pressure, p s g p 7 800 Temperature, F 750 Feed Rate, v./v./hour 2.0 Hydrogen Rate, s.c.i./b 500 Hydrogen Consumption, s.c.i./b 180 Liquid Yield, Vol. percent of Feed 100 Feed Inspections on Total Product:

Gravity, AP! 21 24 Sulfur, Wt. Percent 1. 78 0.35 Conradson Carbon, Wt. Percent 1.90 1.15 Nickel, p.p.rn 0. 39 0.10 Vanadium, p.p.m 0. 44 0.05 Aromatic Rings, W 13. 8 12. 4 Desulfurization, Wt. Percent.--" 80 mery:

The catalytic cracking of feed stocks prepared in accordance with the present invention 'provides for an enhanced yield of high quality products. This is shown by the results that were obtained by the catalytic crack-- ing of the hydrotreated product of Example 111 .as.com.-. pared with the catalytic-cracking of the feed stock for the hydrotreatingstep of Table HI. the catalytic cracking feed stock and the results obtained The composition of 8 Table .IV.

CATALYTIC CRACKING or BLEND or HEAVY CAs OIL VVANDV-VIRGIN-VGAS OIL Blend Composition, Vol. Percenti Deasphalted 01] (16 API) (Table 11)-- S5 Virgin Gas Oil (24 API) 65 7 Not Hydro- Hydrotreatecl treated (Table III) No'rn.The lower carbon yield will permit going to higher conversion, which increases further the gains in naphtha yield and octane number.

From Table IV it will be observed that for the same degree of conversion there was obtained an increased yield of a naphtha fraction having an enhanced octane rating. As is set forth in the note at the bottom of the table, the low carbon yield that is obtained with the feed stock of the present invention permits a greater degree of conversion of the feed stock which, in turn, provides :for a further yield of the high octane naphtha products from catalytic cracking.

EXAMPLE V The improved results of the present invention are not obtainable with deasphalated oils having a Conradson carbon content in excess of about 6.5 weight percent.

Byway of example, a West Texas residuum fraction was deasphalted with a liquefied mixture of propane and a cobalt molybdate catalyst especially prepared to obtain the highest degree of catalyst, activity obtainable with gamma alumina-supported cobalt molybdate catalysts.

' The catalyst consisted of about 15 weight percent of oxides of cobalt and molybdenum supported on gamma 7 alumina, the catalyst having been activated by heat treatare set forth in the following table. in Table V.

Table V Run No D-1-1 D-1-2 D-2-2 D-3-1 D-3-2 Process Conditions-- 7 Fee Rate, v./ v./Hr 0. 99 0.95 0.83 0.89 1. 11 Hydrogen Rate, 5 c t /b. 2, 285 2, 487 2, 439 1, 872 1, 288 Pressure, p.s.i g 80 80 800 800 800 Temperature, F 755 753 783 822 821 7 Liquid Yield, Vol. Percent-. 97. 6 97. 7 95. 7 94. 3 95.6

Product Gas, s.c.f./ Desu1iurization,Wt. Percent 60.8 58. 4 60.2 59. 3 49. 1

Feed

Inspections on Total Product: 7 v

Gravity, API 11.7 17.1 16.7 18.3 20.7 19.0 Sulfur, Wt. Percent 3.34 1.31 1.39. 1. 38 1.36 1.70 Conradson Carbon, Wt. Percent. 10.8 7. 87 7. 61 8. 34 8. 24 9. 6 Ni, p.p.m 12.3 6 40 6. 40 7.60 7. 68 10.52 V, p.p.m 22 7 8. 40 9. 68 5. 12.24 15.96 Fe, p.p.m 12.0 23. 6 5. 10 3. 20 1. 0 2. 70

V Desuliurlzation, Wt. Percen 7 9 Y From Table V it will be observed that under the hydrotreating conditions of the present invention the products that were obtained had. an excessively high Conradson carbon content and an excessively high metals content.

This particular set of experiments is of interest in that it is demonstrated that the use of temperatures of more than about 775'F. does not provide for a satisfactory maximized reduction of Conradson carbon content. Note that runs D-2-2, D-3-1, and D-3-2 which were conducted at temperatures of about 780 and 820 F. provided for products having the highest Conradson carbon content.

The improved results of the present invention'are not obtainable when the entire residuum fraction is subjected to hydrogen treatment.

By way of specific example, a West Texas crude oil residuum fraction was subjected to hydrogen treatment with the results that are noted in Table VI.

Table VI HYDROTREATING OF WEST TEXAS CRUDE RESIDUUM Feed stock: 13.9% West Texas residuum. Catalyst: Cobalt molybdate on alumina.

Conditions:

Pressure, p 9* Temperature, F

Feed Rate, v./v./Hour Hydrogen Rate, s.e.i'.[b Hydrogen Consumption, s.c.t.lb. v 3

Feed

Product Yields on Feed: I 1

C; and Lighter, Wt. Percen 04, Vol. Percen Ci -4309i. Nfiphtha', Vol. Per 430-650 F. eating 011, Vol. Percen 650-1,000 F. Gas Oil, Vol. Percent 1,000 F.+, Vol. Percent mecs t ss r Queer-accur- Inspections on Total Liquid Product Gravity. API.--.; Sulfur, Wt; Percent. Conradson Carbon, Wt. Percent Naphtha Insolubles, Wt. Percent From Table VI it will be observed that the product from the hydrotreating step contained excessively, large amounts of Conradson carbon, nickel, and vanadium and that there was no material reduction of these components as compared with the feed stock. 7 I 1 Having described our invention, vwhatis claimed .is:

1. A method which comprises the steps of deasphalting a petroleum hydrocarbon residuumfeed stock composed v t principally of components boiling above about950F. with a liquefied normally gaseous hydrocarbon-under conditions to. provide" a ga 'phalted .oil having a,.Con 1 radson carbon content of about 4.5 to 6.5, recovering" Q the deasphalted oil, subjecting the recovered deasphalted oil to hydrogen treatment in" the presence of a cobalt molybdate catalyst under conversion conditions including. a pressure withinthe range of about 700 to 950 p.s.i.g,, a

temperature within the range of about 675 to 775 F.,v

a space velocity within the range of about 1 to 3 v./v./hr., and a hydrogen charge rate of about 400 to 2000 cubic feet of hydrogen per barrel of deasphalted oil and recovering as the liquid product from the hydrotreating step a catalytic cracking feed stock having a Conradson carboncontent' of not more than about 4 ,weight percent.

2. A method as in claim 1 wherein the hydrotreating conditions include a pressure of about 750 to 850 p.s.i.-g.,

a temperature of about 700 to 750 F., a space velocity of about 1 to 2 v./v./hr., and a hydrogen charge rate of about 500 cubic feet of hydrogen per barrel of deasphalted oil.

'3. A method as in claim 1 wherein the deasphalted oil is subjected to said hydrotreating operation in admixture.

with a petroleum hydrocarbon virgin gas oilfraction boil ing within the range of about 650 to 950 vF.

4. Amethod as in claim 1 wherein the solution ofdcasphalted oil and liquefied normally gaseous hydrocarbon obtained in the deasphalting step is countercurrently contacted with a wash oil prior to removal of the liquefied normally gaseous hydrocarbon from the deasphalted oil.

5. A method as in claim 4 wherein the liquefied normally gaseous hydrocarbon is a mixture of propane with butane and wherein the wash oil is a fraction of catalytic cracking cycle stock having a specific gravity within the 0 range of about 1.02 to 1.2.-

6. A" method which comprises the steps of distilling a petroleum hydrocarbon crude oil under conditions to molybdate catalyst under conversionconditions including a pressure within the. range of about 700 to 950 p'.s".i.g.,

a temperature within the range ot-about 675 to 775 F., alspace velocity within the range of about 1 to 3 v./v./yhr., and a hydrogen charge rate of about 400 to 2000'cubic feet of hydrogen per barrel of deasphalted oil, recovering as the liquid product from said hydrotreat- I mg step a catalytic cracking feed stock having a Conradson carbon content of not more than about 4 weight percent fsaid catalytic cracking feed stock being further characterized by areduced metals content and a reduced aromatics content, and catalytically cracking said thus- .PE MQd feed stock. I

."References Citedin the-file of this patent e 0 UNITED STATES-PATENTS 2,279,550 Benedict et al. Apr. i4, 1942 2,792,336

Kubicek et al. May 14, 19 57 2,853 ,426 Beet Sept. 23, 1958 

1. A METHOD WHICH COMPRISES THE STEPS OF DEASPHALTING A PETROLEUM HYDROCARBON RESIDUUM FEED STOCK COMPOSED PRINCIPALLY OF COMPONENTS BOILING ABOUE ABOUT 950* F. WITH A LIQUEFIED NORMALLY GASEOUS HYDROCARBON UNDER CONDITIONS TO PROVIDE A DEASPHALTED OIL HAVING A CONRANDSON CARBON CONTENT OF ABOUT 4.5 TO 6.5, RECOVERING THE DEASPHALTED OIL, SUBJECTING THE RECOVERED DEASPHALTED OIL TO DHYDROGEN TREATMENT IN THE PRESENCE OF A COBALT MOLYDBATE CATALYST UNDER CONVERSION CONDITIONS INCLUDING A PRESSURE WITHIN THE RANGE OF ABOUT 700 TO 950 P.S.I.G., A TEMPERATURE WITHIN THE RANGE OF ABOUT 675* TO 775* F., A SPACE VELOCITY WITHIN THE RANGE OF ABOUT 1 TO 3V./V./HR., AND A HYDROGEN CHARGE RATE OF ABOUT 400 TO 2000 CUBIC FEET OF HYDROGEN PER BARREL OF DEASPHALTED OIL AND RECOVERING AS THE LIQUID PRODUCT FROM THE HYDROTREATING STEP A CATALYTIC CRACKING FEED STOCK HAVING CONRADSON CARBON CONTENT OF NOT MORE THAN ABOUT 4 WEIGHT PERCENT. 